In manufacturing industries, such as for instance the automotive industry, often it is desirable to form tubular work pieces that are curved or bent. Some non-limiting examples of applications that are specific to the automotive industry include exhaust system components, frame/chassis components, conduits, etc. Non-automotive applications include copper tube plumbing, furniture frames, boat railings, staircase components, signage, ornamental ironwork, etc. Generally, round stock is used in tube bending. However, square and rectangular tubes and pipes may also be bent in order to meet job-specific requirements.
Rotary draw bending is a known technique for forming a curved section in a tubular work piece. In particular, rotary draw bending is an example of a “form bound” bending procedure in which the tubular work piece is clamped and drawn into the shape of a forming die. A variety of single or multiple bends may be formed in this way, so as to shape the work piece into a desired form. Advantageously, rotary draw bending can be used to form complex shapes out of different types of ductile metal tubing. Unfortunately, a different die set is required for forming each different bending radius.
An example of a freeform bending process is three-roll push bending, in which a tubular work piece is guided between a bending-roll and supporting-rolls. The position of the bending-roll defines the bending radius. Although three-dimensional shaping of tubular work pieces is possible, this technique is best suited for forming simple bends in one plane.
It would be beneficial to provide a method and an apparatus for forming a bend in a portion of a tubular work piece, which overcomes at least some of the above-mentioned limitations of the prior art.